Extraction of Pertechnetate and Perrhenate from Water with Deep-Cavity [CpFe(arene)]+-Derivatized Cyclotriveratrylenes

Technetium-99 (β-, t 1/2 = 2.15 × 105 years) is produced in a 6% fission yield from fission reactors. Technetium-99 continues to be of major concern at various nuclear sites because of its mobility in its most common chemical form during the reprocessing cycle and in the environment. Under these oxic aqueous environments the chemical form of Tc is typically Tc(VII)O4 -, which is difficult to remove. Methods for pertechnetate removal to date have mixed results and pose further environmental concerns. Utilization of new cyclotriveratrylene host materials for the extraction of pertechnetate from 0.9% saline into nitromethane has shown high selectivity and efficiency. A deep-cavity host, tris[cyclopentadienyliron(II) arene]cyclotriguiasylene (2), has shown >95% extraction of pertechnetate and perrhenate into nitromethane from saline in the presence of competing anions, outperforming previously reported materials.